It is an object of the invention to provide a semiconductor device having high breakdown voltage and high withstand strength against destruction.
It is an object of the invention to provide a semiconductor device having high breakdown voltage and high withstand strength against destruction.
In order to solve the above described object, a semiconductor device according to claim 1 includes a resistance layer of a first conductivity type, a plurality of base diffusion regions of a second conductivity type formed in the vicinity of inner surface of the resistance layer and positioned apart from one another, a source diffusion region of the first conductivity type formed in the vicinity of inner surface of each of the base diffusion regions in a region more on the inner side than the edge of each of the base diffusion regions and the source diffusion region has a depth shallower than that of each of the base diffusion regions, a channel region positioned near the edge of each of the base diffusion regions and between the edges of each of the base diffusion regions and edges of each of the source diffusion regions, a gate insulating film positioned at least on each of the channel regions, a gate electrode film positioned on the gate insulating film, and a plurality of buried regions of the second conductivity type provided plurally on the bottom of each of the base diffusion regions and connected to each of the base diffusion regions. Among pairs of adjacent base diffusion regions, between a center of width direction of one base diffusion region and the center of width direction of the other base diffusion region and in a range deeper than the depth of the base diffusion regions and shallower than the bottom of the buried regions, an amount of impurity of the first conductivity type and an amount of the impurity of the second conductivity type are nearly equal. Furthermore, a PN junction between the buried region and the resistance layer is set such that avalanche breakdown does not occur at a voltage at which the buried regions is filled with the depletion layer. Moreover, a width Wm1 of the resistance layer in the part between the buried regions adjacent at the bottom of the same base diffusion region is larger than a width Wm2 of the resistance layer in the part between the buried regions adjacent at the bottoms of the different base diffusion regions.
According to the invention as recited in claim 2, in the semiconductor device according to claim 1, the base diffusion regions have a longitudinal direction, the longitudinal directions are provided parallel to one another, and the buried regions are provided parallel to one another along the longitudinal directions of the base diffusion regions.
According to the invention as recited in claim 3, in the semiconductor device according to claim 1, each of the buried regions includes an active groove formed in the resistance layer and a semiconductor material of the second conductivity type filled in the active groove.
According to the invention as recited in claim 4, in the semiconductor device according to claim 2, widths of the buried regions are equal to each other.
According to the invention as recited in claim 5, in the semiconductor device according to claim 2, lengths of the buried regions are equal.
According to the invention as recited in claim 6, the semiconductor device according to claim 1 includes a plurality of ring-shaped withstand voltage grooves surrounding the base diffusion region and a semiconductor material of the second conductivity type provided in the withstand voltage grooves.
According to the invention as recited in claim 7, the semiconductor device according to claim 1 further includes a source electrode film electrically connected to the source diffusion region and the base diffusion region.
According to the invention as recited in claim 8, the semiconductor device according to claim 1 further includes a drain layer of the same conductivity type as that of the resistance layer and having a higher concentration than that of the resistance layer arranged on a surface opposite to the surface of the resistance layer at which the base diffusion region is formed.
According to the invention as recited in claim 9, the semiconductor device according to claim 1 further includes a collector layer of the conductivity type opposite to that of the resistance layer arranged on a surface opposite to the surface of the resistance layer at which the base diffusion region is formed.
According to the invention as recited in claim 10, the semiconductor device according to claim 1 further includes a Schottky electrode film that forms a Schottky junction with the resistance layer arranged on a surface opposite to the surface of the resistance layer at which the base diffusion region is formed.
According to the invention as recited in claim 11, the semiconductor device according to claim 7 further includes a drain electrode film formed on the surface of the resistance layer on a side having the base diffusion region, and the drain electrode film is electrically connected to the resistance layer and insulated from the source electrode film.
According to the invention as described above, the distance Wm1 between adjacent buried regions among a plurality of buried regions positioned at the bottom of the same base diffusion region is the same as the width Wm1 of the resistance layer between these buried regions. The distance Wm2 between adjacent buried regions positioned at the bottoms of adjacent base diffusion regions can be equal to the width Wm2 of the resistance layer between these buried regions. The distance Wm1 is formed to be larger than the distance Wm2, and avalanche breakdown occurs under the bottom of the part between the buried regions in the base diffusion region.
The source diffusion regions are provided at prescribed intervals along the edge of the base diffusion region, and the source electrode film connected to the source diffusion region is electrically connected to the base diffusion region about the center of a width direction of the base diffusion region.
Therefore, avalanche current generated by avalanche breakdown is not passed through the high resistance part in the base diffusion region under the bottom of the source diffusion region, and therefore high ruggedness can be obtained.
It is noted that when the base diffusion regions and the buried regions are formed in long and narrow shapes, the buried regions are provided parallel in the longitudinal direction of the base diffusion regions.
Accordingly, a semiconductor device with high withstand strength against destruction can be obtained.